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        <h1 id="1-ES6"><a href="#1-ES6" class="headerlink" title="1. ES6"></a>1. ES6</h1><h2 id="1-1-ES6-模块化"><a href="#1-1-ES6-模块化" class="headerlink" title="1.1. ES6 模块化"></a>1.1. ES6 模块化</h2><h3 id="1-1-1-模块化的基本语法"><a href="#1-1-1-模块化的基本语法" class="headerlink" title="1.1.1. 模块化的基本语法"></a>1.1.1. 模块化的基本语法</h3><p>（1）util1.js：</p>
<figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">export</span> <span class="keyword">default</span> <span class="keyword">var</span> a = <span class="number">100</span>;</span><br><span class="line"></span><br><span class="line"><span class="keyword">export</span> <span class="function"><span class="keyword">function</span> <span class="title">foo</span> </span>&#123;</span><br><span class="line">  <span class="built_in">console</span>.log(<span class="string">'util1-foo'</span>);</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
<p><code>export default</code>命令用于指定模块的默认输出。显然，一个模块只能有一个默认输出。</p>
<p>有了默认输出之后，其他模块加载该模块时，import 命令可以为该匿名变量/函数，起<strong>任意的名字</strong>。</p>
<p>上面的代码中，默认输出是一个变量。当然，我们也可以换成<strong>默认输出一个匿名函数</strong>：</p>
<figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">export</span> <span class="keyword">default</span> <span class="function"><span class="keyword">function</span>(<span class="params"></span>) </span>&#123;</span><br><span class="line">  <span class="built_in">console</span>.log(<span class="string">'util1-function'</span>);</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
<p>（2）util2.js：</p>
<figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">export</span> <span class="keyword">var</span> myUtil2 = <span class="string">'this is util2'</span>;</span><br><span class="line"></span><br><span class="line"><span class="keyword">export</span> <span class="function"><span class="keyword">function</span> <span class="title">fn1</span>(<span class="params"></span>) </span>&#123;</span><br><span class="line">  <span class="built_in">console</span>.log(<span class="string">'util2-fn1'</span>);</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="keyword">export</span> <span class="function"><span class="keyword">function</span> <span class="title">fn2</span>(<span class="params"></span>) </span>&#123;</span><br><span class="line">  <span class="built_in">console</span>.log(<span class="string">'util2-fn2'</span>);</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
<p>上方代码中，我把一个变量和两个函数作为了导出。</p>
<p>（3）index.js：</p>
<h3 id="1-1-2-开发环境"><a href="#1-1-2-开发环境" class="headerlink" title="1.1.2. 开发环境"></a>1.1.2. 开发环境</h3><h4 id="1-1-2-1-babel"><a href="#1-1-2-1-babel" class="headerlink" title="1.1.2.1. babel"></a>1.1.2.1. babel</h4><ul>
<li>电脑有 node 环境，运行 npm init</li>
<li>npm install –save-dev babel-core babel-preset-es2015 babel-preset-latest</li>
<li>目录下创建.babelrc 文件</li>
<li>npm install –g babel-cli</li>
<li>babel-version</li>
<li>创建./src/index.js</li>
<li>内容：[1,2,3].map(item =&gt; item + 1)</li>
<li>babel src/index.js</li>
</ul>
<h3 id="1-1-3-webpack"><a href="#1-1-3-webpack" class="headerlink" title="1.1.3. webpack"></a>1.1.3. webpack</h3><ul>
<li>npm install webpack babel-loader –save-dev</li>
<li>配置 webpack.config.js</li>
<li>配置 package.json 中的 scripts</li>
<li>运行 npm start</li>
</ul>
<h3 id="1-1-4-rollup"><a href="#1-1-4-rollup" class="headerlink" title="1.1.4. rollup"></a>1.1.4. rollup</h3><ul>
<li><p>vue、react 都是通过 rollup 来打包的，能尽量简化代码，优化冗余内容</p>
<ul>
<li>npm init</li>
<li>npm i rollup rollup-plugin-node-resolve rollup-plugin-babel<br>babel-plugin-external-helpers babel-preset-latest –save-dev</li>
<li>配置 .babelrc</li>
<li>配置 rollup.config.js</li>
<li>将 webpack 环境的 JS 代码拷贝过来</li>
<li>修改 package.json 的 scripts</li>
<li>运行 npm start</li>
</ul>
</li>
<li><p>rollup 功能单一，webpack 功能强大，学习成本高</p>
</li>
<li><p>参考设计原则和《Linux/Unix 设计思想》</p>
</li>
<li><p>工具要尽量功能单一，可集成，可扩展</p>
</li>
</ul>
<h3 id="1-1-5-JS-众多模块化标准"><a href="#1-1-5-JS-众多模块化标准" class="headerlink" title="1.1.5. JS 众多模块化标准"></a>1.1.5. JS 众多模块化标准</h3><ul>
<li>没有模块化</li>
<li>AMD 成为标准，require.js（CMD）</li>
<li>前端打包工具，使得 nodejs 模块化可以被使用</li>
<li>ES6 出现，想统一现在所有模块化标准</li>
<li>nodejs 积极支持，浏览器尚未统一</li>
<li>可以自造 lib，但不要自造标准</li>
</ul>
<h3 id="1-1-6-一般面试问题解答"><a href="#1-1-6-一般面试问题解答" class="headerlink" title="1.1.6. 一般面试问题解答"></a>1.1.6. 一般面试问题解答</h3><ul>
<li>语法：import export （注意有无 default）</li>
<li>环境：babel 编译 ES6 语法，模块化可用 webpack 和 rollup</li>
<li>扩展：说一下自己对模块化统一的期待</li>
</ul>
<h2 id="1-2-Class-和普通构造函数的区别"><a href="#1-2-Class-和普通构造函数的区别" class="headerlink" title="1.2. Class 和普通构造函数的区别"></a>1.2. Class 和普通构造函数的区别</h2><h3 id="1-2-1-JS-构造函数"><a href="#1-2-1-JS-构造函数" class="headerlink" title="1.2.1. JS 构造函数"></a>1.2.1. JS 构造函数</h3><figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">MathHandle</span> (<span class="params">x,y</span>) </span>&#123;</span><br><span class="line">  <span class="keyword">this</span>.x = x;</span><br><span class="line">  <span class="keyword">this</span>.y = y;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line">MathHandle.prototype.add = <span class="function"><span class="keyword">function</span> (<span class="params"></span>) </span>&#123;</span><br><span class="line">  <span class="keyword">return</span> <span class="keyword">this</span>.x + <span class="keyword">this</span>.y;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="keyword">var</span> m = <span class="keyword">new</span> MathHandle(<span class="number">1</span>, <span class="number">2</span>);</span><br><span class="line"><span class="built_in">console</span>.log(m.add())</span><br></pre></td></tr></table></figure>
<h3 id="1-2-2-Class-基本语法"><a href="#1-2-2-Class-基本语法" class="headerlink" title="1.2.2. Class 基本语法"></a>1.2.2. Class 基本语法</h3><figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br></pre></td><td class="code"><pre><span class="line"><span class="class"><span class="keyword">class</span> <span class="title">MathHandle</span> </span>&#123;</span><br><span class="line">  <span class="keyword">constructor</span>(x, y) &#123;</span><br><span class="line">    <span class="keyword">this</span>.x = x;</span><br><span class="line">    <span class="keyword">this</span>.y = y;</span><br><span class="line">  &#125;</span><br><span class="line"></span><br><span class="line">  add() &#123;</span><br><span class="line">  <span class="keyword">return</span> <span class="keyword">this</span>.x + <span class="keyword">this</span>.y;</span><br><span class="line">  &#125;</span><br><span class="line">&#125;</span><br><span class="line"><span class="keyword">const</span> m = <span class="keyword">new</span> MathHandle(<span class="number">1</span>, <span class="number">2</span>);</span><br><span class="line"><span class="built_in">console</span>.log(m.add())</span><br></pre></td></tr></table></figure>
<h3 id="1-2-3-语法糖"><a href="#1-2-3-语法糖" class="headerlink" title="1.2.3. 语法糖"></a>1.2.3. 语法糖</h3><figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line"><span class="class"><span class="keyword">class</span> <span class="title">MathHandle</span> </span>&#123;</span><br><span class="line">    <span class="comment">// ...</span></span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="keyword">typeof</span> MathHandle <span class="comment">// "function"</span></span><br><span class="line">MathHandle === MathHandle.prototype.constructor <span class="comment">// true</span></span><br><span class="line">m.__proto__ === MathHandle.prototype <span class="comment">// ture</span></span><br></pre></td></tr></table></figure>
<p>构造函数的显式原型有个 constructor 属性等于构造函数本身</p>
<p>new 出来的实例有个隐式原型等于构造函数的显式原型</p>
<h3 id="1-2-4-继承"><a href="#1-2-4-继承" class="headerlink" title="1.2.4. 继承"></a>1.2.4. 继承</h3><h4 id="1-2-4-1-继承-JS"><a href="#1-2-4-1-继承-JS" class="headerlink" title="1.2.4.1. 继承-JS"></a>1.2.4.1. 继承-JS</h4><figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">Animal</span>(<span class="params"></span>) </span>&#123;</span><br><span class="line">    <span class="keyword">this</span>.eat = <span class="function"><span class="keyword">function</span> (<span class="params"></span>) </span>&#123;</span><br><span class="line">        <span class="built_in">console</span>.log(<span class="string">'animal eat'</span>)</span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">Dog</span>(<span class="params"></span>) </span>&#123;</span><br><span class="line">    <span class="keyword">this</span>.bark = <span class="function"><span class="keyword">function</span> (<span class="params"></span>) </span>&#123;</span><br><span class="line">        <span class="built_in">console</span>.log(<span class="string">'dog bark'</span>)</span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="comment">// 绑定原型，实现继承</span></span><br><span class="line">Dog.prototype = <span class="keyword">new</span> Animal()</span><br><span class="line"><span class="keyword">var</span> hashiqi = <span class="keyword">new</span> Dog()</span><br><span class="line">hashiqi.bark() <span class="comment">// dog bark</span></span><br><span class="line">hashiqi.eat() <span class="comment">// animal eat</span></span><br></pre></td></tr></table></figure>
<h4 id="1-2-4-2-继承-class"><a href="#1-2-4-2-继承-class" class="headerlink" title="1.2.4.2. 继承-class"></a>1.2.4.2. 继承-class</h4><figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br></pre></td><td class="code"><pre><span class="line"><span class="class"><span class="keyword">class</span> <span class="title">Animal</span> </span>&#123;</span><br><span class="line">  <span class="keyword">constructor</span>(name) &#123;</span><br><span class="line">    <span class="keyword">this</span>.name = name</span><br><span class="line">  &#125;</span><br><span class="line">    eat() &#123;</span><br><span class="line">      <span class="built_in">console</span>.log(<span class="keyword">this</span>.name + <span class="string">`eat`</span>)</span><br><span class="line">  &#125;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="class"><span class="keyword">class</span> <span class="title">Dog</span> <span class="keyword">extends</span> <span class="title">Animal</span> </span>&#123;</span><br><span class="line">  <span class="keyword">constructor</span>(name) &#123;</span><br><span class="line">    <span class="keyword">super</span>(name) <span class="comment">// super就是被继承的class的constructor</span></span><br><span class="line">    <span class="keyword">this</span>.name = name</span><br><span class="line">  &#125;</span><br><span class="line">  say() &#123;</span><br><span class="line">    <span class="built_in">console</span>.log(<span class="keyword">this</span>.name + <span class="string">'say'</span>)</span><br><span class="line">  &#125;</span><br><span class="line">&#125;</span><br><span class="line"><span class="keyword">const</span> Dog = <span class="keyword">new</span> Dog(<span class="string">'哈士奇'</span>)</span><br><span class="line">dag.say() <span class="comment">// 哈士奇say</span></span><br><span class="line">dog.eat() <span class="comment">// 哈士奇eat</span></span><br></pre></td></tr></table></figure>
<h3 id="1-2-5-面试问题解答"><a href="#1-2-5-面试问题解答" class="headerlink" title="1.2.5. 面试问题解答"></a>1.2.5. 面试问题解答</h3><ul>
<li>Class 在语法上更加贴合面向对象的写法</li>
<li>Class 实现继承更加易读、易理解</li>
<li>更易于写 java 等后端语言的使用</li>
<li>本质还是语法糖，使用 prototype</li>
</ul>
<h2 id="1-3-Promise-的基本语法"><a href="#1-3-Promise-的基本语法" class="headerlink" title="1.3. Promise 的基本语法"></a>1.3. Promise 的基本语法</h2><h3 id="1-3-1-Callback-Hell"><a href="#1-3-1-Callback-Hell" class="headerlink" title="1.3.1. Callback Hell"></a>1.3.1. Callback Hell</h3><figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">loadImg</span>(<span class="params">src, callback, fail</span>) </span>&#123;</span><br><span class="line">  <span class="keyword">var</span> img = <span class="built_in">document</span>.createElement(<span class="string">'img'</span>)</span><br><span class="line">  img.onload = <span class="function"><span class="keyword">function</span> (<span class="params"></span>) </span>&#123;</span><br><span class="line">      callback(img)</span><br><span class="line">  &#125;</span><br><span class="line">  img.onerror = <span class="function"><span class="keyword">function</span> (<span class="params"></span>) </span>&#123;</span><br><span class="line">      fail()</span><br><span class="line">  &#125;</span><br><span class="line">  img.src = src</span><br><span class="line"> &#125;</span><br><span class="line"></span><br><span class="line"><span class="keyword">var</span> src = <span class="string">'http://www.imooc.com/static/img/index/logo_new.png'</span></span><br><span class="line">loadImg(src, <span class="function"><span class="keyword">function</span> (<span class="params">img</span>) </span>&#123;</span><br><span class="line">    <span class="built_in">console</span>.log(img.width)</span><br><span class="line">&#125;, <span class="function"><span class="keyword">function</span> (<span class="params"></span>) </span>&#123;</span><br><span class="line">    <span class="built_in">console</span>.log(<span class="string">'failed'</span>)</span><br><span class="line">&#125;)</span><br></pre></td></tr></table></figure>
<h3 id="1-3-2-Promise-的语法"><a href="#1-3-2-Promise-的语法" class="headerlink" title="1.3.2. Promise 的语法"></a>1.3.2. Promise 的语法</h3><figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">loadImg</span>(<span class="params">src</span>) </span>&#123;</span><br><span class="line">  <span class="keyword">const</span> promise = <span class="keyword">new</span> <span class="built_in">Promise</span>(<span class="function"><span class="keyword">function</span> (<span class="params">resolve, reject &#123;</span></span></span><br><span class="line"><span class="function"><span class="params">    var img = document.createElement(<span class="string">'img'</span></span>)</span></span><br><span class="line"><span class="function">    <span class="title">img</span>.<span class="title">onload</span> = <span class="title">function</span> (<span class="params"></span>) </span>&#123;</span><br><span class="line">      resolve(img)</span><br><span class="line">    &#125;</span><br><span class="line">    img.onerror = <span class="function"><span class="keyword">function</span> (<span class="params"></span>) </span>&#123;</span><br><span class="line">      reject()</span><br><span class="line">    &#125;</span><br><span class="line">    img.src = src</span><br><span class="line">  &#125;)</span><br><span class="line">  <span class="keyword">return</span> promise</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="keyword">var</span> src = <span class="string">'http://www.imooc.com/static/img/index/logo_new.png'</span></span><br><span class="line"><span class="keyword">var</span> result = loadImg(src)</span><br><span class="line"></span><br><span class="line">result.then(<span class="function"><span class="keyword">function</span> (<span class="params">img</span>) </span>&#123;</span><br><span class="line">  <span class="built_in">console</span>.log(img.width)</span><br><span class="line">&#125;, <span class="function"><span class="keyword">function</span> (<span class="params"></span>) </span>&#123;</span><br><span class="line">  <span class="built_in">console</span>.log(<span class="string">'failed'</span>)</span><br><span class="line">&#125;)</span><br><span class="line"></span><br><span class="line">result.then(<span class="function"><span class="keyword">function</span> (<span class="params">img</span>) </span>&#123;</span><br><span class="line">  <span class="built_in">console</span>.log(img.height)</span><br><span class="line">&#125;)</span><br></pre></td></tr></table></figure>
<h3 id="1-3-3-问题解答"><a href="#1-3-3-问题解答" class="headerlink" title="1.3.3. 问题解答"></a>1.3.3. 问题解答</h3><ul>
<li>new Promise 实例，而且要 return</li>
<li>new Promise 时要传入函数，函数有 resolve reject 两个参数</li>
<li>成功时执行 reslove()失败时执行 reject()</li>
<li>then 监听结果</li>
</ul>
<h2 id="1-4-ES6-其他常用功能"><a href="#1-4-ES6-其他常用功能" class="headerlink" title="1.4. ES6 其他常用功能"></a>1.4. ES6 其他常用功能</h2><h3 id="1-4-1-let-const"><a href="#1-4-1-let-const" class="headerlink" title="1.4.1. let/const"></a>1.4.1. let/const</h3><figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">// JS</span></span><br><span class="line"><span class="keyword">var</span> i = <span class="number">10</span>;</span><br><span class="line">i = <span class="number">100</span>;</span><br><span class="line"><span class="keyword">var</span> j = <span class="number">20</span>;</span><br><span class="line">j = <span class="number">200</span>;</span><br><span class="line"></span><br><span class="line"><span class="comment">// ES6</span></span><br><span class="line"><span class="keyword">let</span> i = <span class="number">10</span>;</span><br><span class="line">i = <span class="number">100</span>;    <span class="comment">// 正确</span></span><br><span class="line"><span class="keyword">const</span> j = <span class="number">20</span>;</span><br><span class="line">j = <span class="number">200</span>;    <span class="comment">// 报错</span></span><br></pre></td></tr></table></figure>
<h3 id="1-4-2-多行字符串-模板变量"><a href="#1-4-2-多行字符串-模板变量" class="headerlink" title="1.4.2. 多行字符串/模板变量"></a>1.4.2. 多行字符串/模板变量</h3><figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">// JS</span></span><br><span class="line"><span class="keyword">var</span> name = <span class="string">'zhangsan'</span>, age = <span class="number">20</span>, html = <span class="string">''</span>;</span><br><span class="line">html += <span class="string">'&lt;div&gt;'</span>;</span><br><span class="line">html += <span class="string">' &lt;p&gt;'</span> + name + <span class="string">'&lt;/p&gt;'</span>;</span><br><span class="line">html += <span class="string">' &lt;p&gt;'</span> + age + <span class="string">'&lt;/p&gt;'</span>;</span><br><span class="line">html += <span class="string">'&lt;/div&gt;'</span>;</span><br><span class="line"></span><br><span class="line"><span class="comment">// ES6</span></span><br><span class="line"><span class="keyword">const</span> name = <span class="string">'zhangsan'</span>, age = <span class="number">20</span>;</span><br><span class="line"><span class="keyword">const</span> html = <span class="string">`&lt;div&gt;</span></span><br><span class="line"><span class="string">              &lt;p&gt;<span class="subst">$&#123;name&#125;</span>&lt;/p&gt;</span></span><br><span class="line"><span class="string">              &lt;p&gt;<span class="subst">$&#123;age&#125;</span>&lt;/p&gt;</span></span><br><span class="line"><span class="string">              &lt;/div&gt;`</span>;</span><br><span class="line"><span class="built_in">console</span>.log(html);</span><br></pre></td></tr></table></figure>
<h3 id="1-4-3-解构赋值"><a href="#1-4-3-解构赋值" class="headerlink" title="1.4.3. 解构赋值"></a>1.4.3. 解构赋值</h3><figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">// JS</span></span><br><span class="line"><span class="keyword">var</span> obj = &#123;<span class="attr">a</span>: <span class="number">100</span>, <span class="attr">b</span>: <span class="number">200</span>&#125;</span><br><span class="line"><span class="keyword">var</span> a = obj.a</span><br><span class="line"><span class="keyword">var</span> b = obj.b</span><br><span class="line"></span><br><span class="line"><span class="keyword">var</span> arr = [<span class="string">'xxx'</span>, <span class="string">'yyy'</span>, <span class="string">'zzz'</span>]</span><br><span class="line"><span class="keyword">var</span> x = arr[<span class="number">0</span>]</span><br><span class="line"></span><br><span class="line"><span class="comment">//ES6</span></span><br><span class="line"><span class="keyword">const</span> obj = &#123;<span class="attr">a</span>: <span class="number">10</span>, <span class="attr">b</span>: <span class="number">20</span>, <span class="attr">c</span>: <span class="number">30</span>&#125;</span><br><span class="line"><span class="keyword">const</span> &#123;a, c&#125; = obj</span><br><span class="line"><span class="built_in">console</span>.log(a)</span><br><span class="line"><span class="built_in">console</span>.log(c)</span><br><span class="line"></span><br><span class="line"><span class="keyword">const</span> arr = [<span class="string">'xxx'</span>, <span class="string">'yyy'</span>, <span class="string">'zzz'</span>]</span><br><span class="line"><span class="keyword">const</span> [x, y, z] = arr</span><br><span class="line"><span class="built_in">console</span>.log(x)</span><br><span class="line"><span class="built_in">console</span>.log(y)</span><br><span class="line"><span class="built_in">console</span>.log(z)</span><br></pre></td></tr></table></figure>
<h3 id="1-4-4-块级作用域"><a href="#1-4-4-块级作用域" class="headerlink" title="1.4.4. 块级作用域"></a>1.4.4. 块级作用域</h3><figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">// JS</span></span><br><span class="line"><span class="keyword">var</span> obj = &#123;<span class="attr">a</span>: <span class="number">100</span>, <span class="attr">b</span>:<span class="number">200</span>&#125;</span><br><span class="line"><span class="keyword">for</span> (<span class="keyword">var</span> item <span class="keyword">in</span> obj) &#123;</span><br><span class="line">    <span class="built_in">console</span>.log(item)</span><br><span class="line">&#125;</span><br><span class="line"><span class="built_in">console</span>.log(item) <span class="comment">// 'b'</span></span><br><span class="line"></span><br><span class="line"><span class="comment">// ES6</span></span><br><span class="line"><span class="keyword">const</span> obj = &#123;<span class="attr">a</span>:<span class="number">100</span>, <span class="attr">b</span>:<span class="number">200</span>&#125;</span><br><span class="line"><span class="keyword">for</span> (<span class="keyword">let</span> item <span class="keyword">in</span> obj) &#123;</span><br><span class="line">    <span class="built_in">console</span>.log(item)</span><br><span class="line">&#125;</span><br><span class="line"><span class="built_in">console</span>.log(item) <span class="comment">// undefined</span></span><br></pre></td></tr></table></figure>
<h3 id="1-4-5-函数默认参数"><a href="#1-4-5-函数默认参数" class="headerlink" title="1.4.5. 函数默认参数"></a>1.4.5. 函数默认参数</h3><figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">// JS</span></span><br><span class="line"><span class="function"><span class="keyword">function</span> (<span class="params">a, b</span>) </span>&#123;</span><br><span class="line">    <span class="keyword">if</span> (b == <span class="literal">null</span>) &#123;</span><br><span class="line">        b = <span class="number">0</span></span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="comment">// ES6</span></span><br><span class="line"><span class="function"><span class="keyword">function</span> (<span class="params">a, b=<span class="number">0</span></span>) </span>&#123;</span><br><span class="line"></span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
<h3 id="1-4-6-箭头函数-this"><a href="#1-4-6-箭头函数-this" class="headerlink" title="1.4.6. 箭头函数(this)"></a>1.4.6. 箭头函数(this)</h3><figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">// JS</span></span><br><span class="line"><span class="keyword">var</span> arr = [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>]</span><br><span class="line">arr.map(<span class="function"><span class="keyword">function</span> (<span class="params">item</span>) </span>&#123;</span><br><span class="line">    <span class="keyword">return</span> item + <span class="number">1</span></span><br><span class="line">&#125;)</span><br><span class="line"></span><br><span class="line"><span class="comment">// ES6</span></span><br><span class="line"><span class="keyword">const</span> arr = [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>]</span><br><span class="line">arr.map(<span class="function"><span class="params">item</span> =&gt;</span> item + <span class="number">1</span>);</span><br><span class="line">arr.map(<span class="function">(<span class="params">item, index</span>) =&gt;</span> &#123;</span><br><span class="line">    <span class="built_in">console</span>.log(index)</span><br><span class="line">    <span class="keyword">return</span> item + <span class="number">1</span></span><br><span class="line">&#125;)</span><br></pre></td></tr></table></figure>
<figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">fn</span>(<span class="params"></span>) </span>&#123;</span><br><span class="line">  <span class="built_in">console</span>.log(<span class="string">'real'</span>, <span class="keyword">this</span>)</span><br><span class="line">  <span class="keyword">var</span> arr = [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>]</span><br><span class="line"></span><br><span class="line">  <span class="comment">// JS</span></span><br><span class="line">  arr.map(<span class="function"><span class="keyword">function</span> (<span class="params">item</span>) </span>&#123;</span><br><span class="line">    <span class="built_in">console</span>.log(<span class="string">'js'</span>, <span class="keyword">this</span>)</span><br><span class="line">    <span class="keyword">return</span> item + <span class="number">1</span></span><br><span class="line">  &#125;)</span><br><span class="line"></span><br><span class="line">  <span class="comment">// ES6</span></span><br><span class="line">  arr.map(<span class="function"><span class="params">item</span> =&gt;</span> &#123;</span><br><span class="line">    <span class="built_in">console</span>.log(<span class="string">'es6'</span>, <span class="keyword">this</span>)</span><br><span class="line">    <span class="keyword">return</span> item + <span class="number">1</span></span><br><span class="line">  &#125;)</span><br><span class="line">&#125;</span><br><span class="line">fn.call(&#123;<span class="attr">a</span>: <span class="number">100</span>&#125;)</span><br></pre></td></tr></table></figure>

      
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              <div class="post-toc-content"><ol class="nav"><li class="nav-item nav-level-1"><a class="nav-link" href="#1-ES6"><span class="nav-text">1. ES6</span></a><ol class="nav-child"><li class="nav-item nav-level-2"><a class="nav-link" href="#1-1-ES6-模块化"><span class="nav-text">1.1. ES6 模块化</span></a><ol class="nav-child"><li class="nav-item nav-level-3"><a class="nav-link" href="#1-1-1-模块化的基本语法"><span class="nav-text">1.1.1. 模块化的基本语法</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#1-1-2-开发环境"><span class="nav-text">1.1.2. 开发环境</span></a><ol class="nav-child"><li class="nav-item nav-level-4"><a class="nav-link" href="#1-1-2-1-babel"><span class="nav-text">1.1.2.1. babel</span></a></li></ol></li><li class="nav-item nav-level-3"><a class="nav-link" href="#1-1-3-webpack"><span class="nav-text">1.1.3. webpack</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#1-1-4-rollup"><span class="nav-text">1.1.4. rollup</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#1-1-5-JS-众多模块化标准"><span class="nav-text">1.1.5. JS 众多模块化标准</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#1-1-6-一般面试问题解答"><span class="nav-text">1.1.6. 一般面试问题解答</span></a></li></ol></li><li class="nav-item nav-level-2"><a class="nav-link" href="#1-2-Class-和普通构造函数的区别"><span class="nav-text">1.2. Class 和普通构造函数的区别</span></a><ol class="nav-child"><li class="nav-item nav-level-3"><a class="nav-link" href="#1-2-1-JS-构造函数"><span class="nav-text">1.2.1. JS 构造函数</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#1-2-2-Class-基本语法"><span class="nav-text">1.2.2. Class 基本语法</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#1-2-3-语法糖"><span class="nav-text">1.2.3. 语法糖</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#1-2-4-继承"><span class="nav-text">1.2.4. 继承</span></a><ol class="nav-child"><li class="nav-item nav-level-4"><a class="nav-link" href="#1-2-4-1-继承-JS"><span class="nav-text">1.2.4.1. 继承-JS</span></a></li><li class="nav-item nav-level-4"><a class="nav-link" href="#1-2-4-2-继承-class"><span class="nav-text">1.2.4.2. 继承-class</span></a></li></ol></li><li class="nav-item nav-level-3"><a class="nav-link" href="#1-2-5-面试问题解答"><span class="nav-text">1.2.5. 面试问题解答</span></a></li></ol></li><li class="nav-item nav-level-2"><a class="nav-link" href="#1-3-Promise-的基本语法"><span class="nav-text">1.3. Promise 的基本语法</span></a><ol class="nav-child"><li class="nav-item nav-level-3"><a class="nav-link" href="#1-3-1-Callback-Hell"><span class="nav-text">1.3.1. Callback Hell</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#1-3-2-Promise-的语法"><span class="nav-text">1.3.2. Promise 的语法</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#1-3-3-问题解答"><span class="nav-text">1.3.3. 问题解答</span></a></li></ol></li><li class="nav-item nav-level-2"><a class="nav-link" href="#1-4-ES6-其他常用功能"><span class="nav-text">1.4. ES6 其他常用功能</span></a><ol class="nav-child"><li class="nav-item nav-level-3"><a class="nav-link" href="#1-4-1-let-const"><span class="nav-text">1.4.1. let/const</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#1-4-2-多行字符串-模板变量"><span class="nav-text">1.4.2. 多行字符串/模板变量</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#1-4-3-解构赋值"><span class="nav-text">1.4.3. 解构赋值</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#1-4-4-块级作用域"><span class="nav-text">1.4.4. 块级作用域</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#1-4-5-函数默认参数"><span class="nav-text">1.4.5. 函数默认参数</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#1-4-6-箭头函数-this"><span class="nav-text">1.4.6. 箭头函数(this)</span></a></li></ol></li></ol></li></ol></div>
            

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